AbstractThe megacity of Beijing, China, has had an air pollution problem since the 1990s. The concentrations of particulate matter with an aerodynamic diameter less than 10 mu m (PM 10) in Beijing in the winter of 2000 were high; the average value of 188 mu g m(-3) was nearly four times the first grade national standard of 50 mu g m(-3). The CALPUFF modeling system was used to simulate PM 10 dispersion from I January 2000 to 29 February 2000. We used near real-time landcover data from the moderate resolution imaging spectroradiometer (MODIS). Statistical evaluation indicated that the model agreed well with the observations. The fluctuations of 24-h PM 10 concentrations followed the winter synoptic winds. Cold air from the northwest or north intruded over Beijing for average periods of 4 days in winter, accompanied by high wind speeds. PM 10 was swept out of Beijing after the cold fronts and accumulated again once the winds stopped, until the next cold air intrusion. Capital Steel Corporation Limited contributed 46% of the PM10 mass concentrations observed in the Shijingshan industrial area, and had little effect on the eastern part or the center of Beijing. The other industrial regions distributed in southeastern Beijing accounted for an average of 18% of the PM10 in Beijing. Boilers associated with coal consumption mostly for winter heating contributed 31%. Motor vehicles and road dust contributed 5% and 13%, respectively. The total of residential heating in old houses and restaurants contributed approximately 7%. The primary PM10 emissions from electrical generating units were relatively low. Some suggestions are proposed for reducing PM10 pollution in Beijing. (c) 2006 Elsevier Ltd. All rights reserved.